Electron switching device



Sept. 8, 1953 V J. J. B. LAIR 2,651,740

ELECTRON SWITCHING DEVICE Filed Sept. 29, 19's; .2 Sheets-Sheet 2 H II:

4 :OLTAGE UURCE 1F INVENTOR JUL/EN L/. B. LAII? v ATTORNEY Patented Sept. 8, 1953 ELECTRON SWITCHING DEVICE J ulien J. B. Lair, Nutley, N. J assignor to Federal Telecommunication Laboratories, Inc., Nutley, N. J a corporation of Delaware Application September 29, 1951, Serial No. 248,999

17 Claims. 1

This invention relates to electron switching devices, and more particularly to electron switching circuits utilizing multigap cold cathode gasfilled electron tubes.

Attempts have been made heretofore to provide electron switching devices of the cold cathode gas-filled type for counting electric pulses at a very rapid speed. Usually such devices have employed transfer electrodes in addition to the oathodes or had specially shaped electrodes to provide 1 switching in one direction only. Very rapid operation, in tubes of known design, is impeded because of the time required for glow spread on a directional cathode or the time to establish the glow and priming of the transfer electrodes. Another disadvantage of these known tubes is the critical nature of the spacing between the cathodes.

One of the objects of this invention, therefore, is to provide an electron switching device which overcomes the aforementioned objections.

Another object of this invention is to provide an electron switching device in which the energy and time duration requirements are exceptionally small so as to be capable of rapid switching operation.

A further object of this invention is to provide a bias control system for multi-electrode switching devices whereby bias is applied from electrode to electrode as successive electrodes are caused to conduct.

Briefly, in the electron switching device of this invention, a cold cathode electron tube is provided having a common anode and a plurality of cathodes spaced to provide a plurality of anodecathode gaps. Associated with each cathode is a bias control circuit, and in coupling relation between such bias control circuits are directive couplings. The conduction at any one anodecathode gap provides a potential bias through these directive couplings to bias in stair step relation, the other anode-cathode gaps. When the next triggering potential is applied, the most favorably biased, and in some embodiments the best primed gap, is fired.

The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent by reference to the following description taken in conjunction with the accompanying drawings, where- Fig. 1 is a schematic diagram of a glow discharge tube and associate circuit employed in one embodiment of this invention; and

Figs. 2, 3, and 4 are schematic diagrams of modified embodiments of this invention.

Referring to Fig. 1, a cold cathode gas-filled electron tube I, according to this invention, may comprise an envelope 2 containing a gaseous atmosphere, an anode 3, a plurality of cathodes 4 to 8, and a plate electrode 9. The gap between anode 3 and cathode 4 will be designated as gap 3-4, and the gaps between the other cathodes and the anode are hereinafter designated in a like manner. The plate electrode 9 is connected to a source of voltage l 0 to provide a positive bias adjacent the cathodes whereby the active cathode areas are limited. The ends of the cathodes may comprise any desired shape, and where plate 9 is used the cathodes may be in simple pin form. A circuit comprising a resistor I I is connected to anode 3 to impress thereon a substantially continuous positive potential from source I 3.

Associated with the cathodes 4 to 8 is a bias control system comprising a plurality of control circuits coupled together by rectifiers M to I8. Each bias control circuit includes a pair of resistors connected together in series and to one of the cathodes. These resistors are indicated by reference characters 9 to 23 and 24 to 28, respectively. One each of the condensers 29 to 33 is connected in parallel across each pair of resistors. The control circuits are connected to ground through a resistor 34.

In any tube of this general classification, uniformity of the characteristics of the cathodeanodegaps is essential. This means that the cathode area should be defined within relatively close limits. This is accomplished by the provision of plate 9 which is disposed adjacent the ends of the cathodes. The voltage bias of plate 9 is preferably slightly more positive than the voltage bias of anode 3. For additional information on tube constructions that may be employed with the present invention, reference may be had to the copendin applicatoin of M. W. Wallace, Serial No. 253,284, filed October 26, 1951, entitled Cold Cathode Discharge Tubes.

To illustrate the operation of this invention assume that the anode supply voltage I3 initially applied is sufficient to fire one of the anodecathode gaps. When one of the gaps, assuming gap 36, begins to conduct, the voltage on the anode 3 drops due to the anode load resistor It] to a value slightly above the maintaining voltage; thus maintaining conduction at the first gap to break down. Also, due to the resistors 2| and 26 in the associated control circuit, the conducting cathode 6 assumes a positive voltage with respect to the common point on the ground side of the cathode network. Part of this positive bias is fed through rectifier IE to the next cathode 5 to the left, and this voltage is again divided and a still lower voltage applied through rectifier l to cathode 4. This continues around the re-entrant system establishing a staircase of voltages V5, V4, V8, and V7 on the cathodes 5, 4, 8, and i. This staircase will descend in the opposite direction to that in which the tube will switch, and voltages being established in such a manner that:

For the sake of symmetry all the cathode resistors are equal. When a glow exists in a gap such as 36, the proportional values of the voltage introduced at the other cathodes is a function of the ratio of the associated resistors such as resistor 2| to resistor 26 for cathode 6.

This will make the potential drop across gaps 38 and 3'l the greatest. In addition, cathode I being nearer to cathode 6 which is firing, is primed more than cathode 8. On the arrival of a positive input pulse fed into the circuit through condenser 35, or a negative input pulse fed into the circuit through condenser 35, the potential across the gap is reduced thereby extinguishing conduction in gap 3. If the input pulse is short with respect to the discharge time of the control circuits, the adjacent cathode 'l fires upon decay of the input pulse. Only this one cathode 1 fires because of the fact that its striking voltage is reduced more than gap 38 by the priming effect of the adjacent discharge across the gap 36. The gap 38 being further away from gap 35 is not so primed and therefore will not fire when gap 3---'! fires. After ignition of gap 3-1, the gap potentials assume the following relationship:

When the next input pulse is received, the process is repeated, that is, gap 31 is extinguished and gap 3-8 is ignited. Since the cathodes are, in practice, disposed in a circle or endless chain, gap 34 is adjacent gap 38 and will, upon application of the next impulse, ignite in the manner described above. The output may be taken ofi of either the anode resistor H or cathode resistor 34 as may be desired depending upon application of input pulses.

A modified embodiment of this invention is shown in Fig. 2 wherein gap potentials all differ. The addition of resistors 31 to 4|, one in parallel with the series resistors of each control circuit, results in establishing a staircase of voltages which will descend all the way along the series of cathodes. Assuming that gap 3a-6a is firing, the

cathode biasing voltages will be established in instead of the staircase established by the embodiment shown in Fig. 1 taking cathode 55. as typical, it is obvious that the biasing voltage is modified by the value Rsa of resistor 38 divided by the value R20 of resistor 203. plus the value of Rise of resistor 38, or

which is always less than unity.

Thus we have the biasing voltage V5 on cathode 5 equal to the voltage Vs on cathode 6 multiplied by the above fraction showing that Referring to Fig. 3, wherein another embodiment of this invention is shown, a cold cathode gas-filled electron tube 42 comprises an envelope 43 to 54. A circuit comprising a resistor 55 is coupled to anode 44 so that a positive Potential from source 51 may be impressed on anode 44. External to said envelope 43 and associated with cathodes 45 to 54 are a plurality of bias control circuits comprising rectifier 58 to 61, series resistors 68 to H and 18 to 81, respectively, and resistors 88 to 97 disposed in parallel with the series resistors 68 to 81. The control circuits are connected to ground through a common resistor. The control circuits are directionally coupled together in a given relation by rectifiers 58 to El, and the cathodes 45 to 54 are connected to the control circuits in a staggered relation such that if the gap 43-54 is firing, a voltage V54 appears on cathode 54 and the following relations exist between the voltages developed at the other cathodes.

Due to the ionization coupling, only those cathodes 53, 45, 52, and 46 nearest the cathode 54, the cathodes being normally disposed in a circle, will compete for the discharge. The distribution of biasing voltages among these cathodes is such that Since cathode 53 has the least biasing potential, and therefore the gap thereof has the greatest potential difference, it will be the next to fire. By the use of this staggered connecting arrangement a greater potential difference is obtained with respect to adjacent cathodes than where the connections are consecutive.

Another embodiment of this invention is shown in 4, wherein the control circuits include resistors 93 to I82 which connect the cathodes in staggered relation to ground through a common resistor N13. The control circuits also include resistors N39 to H3 which connect the cathode connections of resistors 98 to I02 in series with coupling rectifiers I64 to I03. Assuming cathode ll4| i8 is fired, the biasing voltages appearing on the other cathodes will be such that Cathode H4 is adjacent to cathode H5 and to cathode H8, the cathodes being in practice arranged in a circle. Cathode I I5 will be the next to fire, and there will be no chance of any other cathode firing due to the great difference in the biasing voltages and the more pronounced priming of the adjacent cathodes.

While the cathodes of Figs. 2, 3, and 4 are not shown provided with area limiting electrodes such as electrode 9 in Fig. 1, such are contemplated where speed of switching operation is important.

Many variations in. the structure and circuits of the embodiments shown will occur to those skilled in the art, and for this reason it should be understood that the particular embodiments disclosed in this application are to be regarded as illustrative only and not as a limitation to the invention as set forth in the objects thereof and the accompanying claims.

I claim:

1. An electron switching device comprising an envelope containing a gaseous atmosphere, an anode and a plurality of cathodes, said cathodes being disposed in spaced relation to each other and to said anode to provide a plurality of anode-cathode gaps, a plurality of bias control circuits each coupled to one of said cathodes, each control circuit having at least one resistor, directive means coupling each of said control circuits to another of said control circuits, the circuit connection between cathodes including one of said directional means and a resistor of one of said control circuits, whereby the firing of one anode-cathode gap provides a potential bias through the associated directive coupling means to bias the anodecathode gaps associated with the other control circuits at different potential levels, and means for applying a pulse potential difference across said gaps to fire the gap having the most favorabie condition.

An electron switching device according to claim 1, wherein the means for applying a pulse potential difference across said gaps includes a circuit coupled to said anode.

3. An electron switching device according to claim 1, wherein the means for applying a pulse potential difference across said gaps includes a circuit coupled to said bias control circuits.

4. An electron switching device according to claim 1, wherein each directive coupling means comprises a rectifier.

5. An electron switching device according to claim 1, wherein each bias control circuit includes a pair of resistors connected in series to the cathode associated with such control circuit and a condenser disposed in parallel with said resistors, and wherein said directive coupling means is disposed in coupling relation between the common junction of said pair of resistors and another of said cathodes.

6. An electron switching device according to claim 5, wherein each bias control circuit further includes a resistor disposed in parallel to said condenser.

7. An electron switching device according to claim 1, wherein each bias control circuit includes a network of resistors comprising a pair of resistors connected in series to the cathode associated with such control circuit and a third resistor connected in parallel with said pair of resistors, and the directive coupling means is disposed in coupling relation between the common junction of said pair of resistors and another of said cathodes.

8. An electron switching device according to claim 1, wherein each bias control circuit comprises a resistor connected in series with the cathode associated with such control circuit and a second resistor connected between the cathode connection to said first mentioned resistor and a directive coupling means associated with another of said bias control circuits.

9. An electron switching device according to claim 1, wherein the bias control circuits and said directive coupling means are disposed to form an endless chain.

10. An electron switching device according to claim 9, wherein the bias control circuits includes a connection to a common resistor and said means for applying pulse potential difierence across said gaps includes a circuit connected to said common resistor connection.

11. An electron switching device according to claim 1, wherein said cathodes are disposed in a given successive relationship and said control circuits are coupled in a given successive relationship but the connections between said cathodes and said control circuits are diiferent from said give successive relationships.

12. A bias control system for a plurality of electrodes of a multi-electrode device comprising a plurality of bias control circuits each having at least one resistor and a desired time constant characteristic for association with one of the electrodes of said device coupled to the cathode associated with one of said control circuits and in series with the resistor of another of said control circuits, means coupling each of said control circuits to another of said control circuits, the coupling means between successive control circuits each including a rectifier, whereby the conduction in the circuit of any one of said electrodes provides potential bias through said coupling means to said control circuits at different potential levels depending on the remoteness in a given direction of the respective control circuit from the conducting circuit.

13. A bias control system according to claim 12, wherein each bias control circuit includes a pair of resistors connected in series and a condenser disposed in parallel with said resistors, and wherein said coupling means is disposed in coupling relation between the common junction of said pair of resistors and another of said control circuits.

1a. A bias control system according to claim 13, wherein each bias control circuit further includes a resistor disposed in parallel to said condenser.

15. A bias control system according to claim 12, wherein each bias control circuit includes a pair of resistors connected in series and a third resistor connected in parallel with said pair of resistors, and the coupling means is disposed in coupled relation between the common junction of said pair of resistors and another of said control circuits.

18. A bias control system according to claim 12, wherein each bias control circuit comprises a resistor adapted for connection in series with one of the electrodes of said device and a second resistor connected to said first resistor in series with one of the coupling means associated therewith.

17. A bias control system according to claim 12, wherein the bias control circuits and said coupling means are disposed to form an endless chain.

JULIEN J. B. LAIR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,515,448 Gulden July 18, 1950 2,547,008 Hough Apr. 3, 1951 2,549,779 Crenshaw Apr. 24, 1951 2,575,517 Hagen Nov. 20, 1951 2,579,306 Depew Dec. 18, 1951 

